AP Biology Immune / Lymphatic System lymphocytes attacking cancer cell phagocytic leukocyte lymph system Fighting the Enemy Within!

AP Biology Objectives  3 lines of defense  Non-specific vs specific defense  Active vs passive immunity  Antibody structure and function  Humoral vs cell-mediated responses

AP Biology Agents of disease (PATHOGENS)  Viruses  Bacteria  Protists  Fungi

AP Biology How do diseases spread  Physical contact  Contaminated food and water  Infected animals/ VECTORS  Insects/ arachnids

AP Biology Types of diseases  Viral – measles, mumps, HIV, flu, cold, chickenpox  Bacterial – strep throat, cholera, botulism, bubonic plague, staph infection, Lyme’s disease  Protist – dysentery, malaria, African sleeping sickness  Fungal – athletes foot, ringworm, Candida, thrush

AP Biology Avenues of attack  Points of entry  digestive system  respiratory system  urogenital tract  break in skin  Routes of attack  circulatory system  lymph system

AP Biology Non-specific Defense 1. 1 st : Barriers (skin/ mucous membranes) 2. 2 nd : Non-specific patrol (phagocytic WBC’s) 3. 2 nd : Immune Response 4. 2 nd : Fever 1 st Line of Defense 2 nd Line of Defense

AP Biology Non-specific Lines of defense  1st line: Barriers  broad, external defense  “walls & moats”  skin & mucus membranes  2nd line: Non-specific patrol  broad, internal defense  “patrolling soldiers”  leukocytes = phagocytic WBC  macrophages Bacteria & insects inherit resistance. Vertebrates acquire immunity!

AP Biology 1 st and 2 nd lines of defense are NON-SPECIFIC

AP Biology 1st line: External defense  Physical & chemical defenses  non-specific defense  external barrier  epithelial cells & mucus membranes  skin  respiratory system  digestive system  uro-genital tract Lining of trachea: ciliated cells & mucus secreting cells

AP Biology 1st line: Chemical barriers on epithelium  Skin & mucous membrane secretions  sweat  pH 3-5  tears  washing action  mucus  traps microbes  saliva  anti-bacterial enzymes  stomach acid  pH 2

AP Biology 2nd line: Internal, broad range patrol leukocytes  Innate, general defense  rapid response  Patrolling cells & proteins  attack invaders that penetrate body’s outer barriers  leukocytes  phagocytic white blood cells  Interferons  complement system  anti-microbial proteins  inflammatory response

AP Biology Interferons  Interferons are proteins made and released by host cells in response to the presence of pathogens such as viruses, bacteria, parasites or tumor cells.  Interferon therapy (IF) can be helpful in alleviating symptoms of viral disease but DO NOT eradicate the virus.

AP Biology Phagocytes = eating cells yeast macrophage

AP Biology 2 nd line: Inflammatory Response  t/animations/content/inflammatory.html t/animations/content/inflammatory.html

AP Biology Inflammatory response  Triggered by damage to tissue  triggers local non-specific inflammatory response  release histamines  capillaries dilate, more permeable (leaky)  increase blood supply  delivers WBC, RBC, platelets, clotting factors  fight pathogens  clot formation  accounts for swelling, redness & heat of inflammation & infection

AP Biology Inflammatory response Bacteria Blood vessel Chemical alarm signals Pin or splinter Blood clot Phagocytes swelling  Reaction to tissue damage

AP Biology 2 nd line: Fever  When a local response is not enough  higher temperature helps defense  inhibits bacterial growth  Increases heart rate – WBC’s can get to infection faster  speeds up repair of tissues  causes liver & spleen to store iron, reducing blood iron levels  bacteria need large amounts of iron to grow

AP Biology Non-specific Defense  Barriers – 1 st Line  Non-specific patrol – 2 nd Line  Immune Response – 2 nd Line  Fever – 2 nd Line

AP Biology When this is not enough, Our third line of defense kicks in

AP Biology Specific Line of defense  3rd line: Immune response  specific, acquired immunity  “elite trained units”  Foreign invader (called an antigen) triggers this response  Cells involved  Lymphocytes  B cells Humoral response  T cells Cell-mediated response

AP Biology Immune Response  hill.com/sites/ /student_view 0/chapter22/animation__the_immune_r esponse.html hill.com/sites/ /student_view 0/chapter22/animation__the_immune_r esponse.html

AP Biology “self”“foreign” How are invaders recognized: antigens  Antigens  proteins that serve as cellular name tags  foreign antigens cause response from WBCs  viruses, bacteria, protozoa, parasitic worms, fungi, toxins  non-pathogens: pollen & transplanted tissue  B cells & T cells respond to different antigens  B cells recognize intact antigens  pathogens in blood & lymph  T cells recognize antigen fragments  pathogens which have already infected cells

AP Biology Key attributes of a good immune system  4 attributes that characterize the immune system as a whole  specificity  antigen-antibody specificity  diversity  react to millions of antigens  memory  rapid 2° response  ability to distinguish self vs. non-self  maturation & training process to reduce auto-immune disease

AP Biology B cells  Humoral response = “in fluid”  defense against attackers circulating freely in blood & lymph  Specific response  produce specific antibodies against specific antigen  Types of B cells  plasma cells  immediate production of antibodies  rapid response, short term release  memory cells  Stay in body  Recognizes invader on future infections  long term immunity

AP Biology B cell immune response tested by B cells (in blood & lymph) 10 to 17 days for full response invader (foreign antigen) B cells + antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y recognition Y Y Y Y Y Y Y Y clone 1000s of clone cells Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y plasma cells release antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y memory cells “reserves” Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y YY Y Y captured invaders

AP Biology Antibodies  Proteins that bind to a specific antigen  multi-chain proteins produced by B cells  binding region matches molecular shape of antigens  each antibody is unique & specific  millions of antibodies respond to millions of foreign antigens  tagging “handcuffs”  “this is foreign…gotcha!” each B cell has ~100,000 antigen receptors Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y antigen antigen- binding site on antibody variable binding region

AP Biology s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s Structure of antibodies light chains antigen-binding site heavy chains antigen-binding site light chain light chain heavy chains B cell membrane variable region antigen-binding site Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y

AP Biology How antibodies work macrophage eating tagged invaders invading pathogens tagged with antibodies Y Y Y Y Y Y

AP Biology Huh?  Antibodies = proteins (Y-shaped)… DEFEND you against pathogens.  Your body makes these in response to antigens  Antigens = proteins that GENerate the immune response (are bound up by antibodies)

AP Biology 1° vs 2° response to disease  Memory B cells allow a rapid, amplified response with future exposure to pathogen

AP Biology Vaccinations  Immune system exposed to harmless version of pathogen  triggers active immunity  stimulates immune system to produce antibodies to invader  rapid response if future exposure  Most successful against viral diseases

AP Biology  Obtaining antibodies from another individual  Maternal immunity  antibodies pass from mother to baby across placenta or in mother’s milk  critical role of breastfeeding in infant health  mother is creating antibodies against pathogens baby is being exposed to  Injection  injection of antibodies  short-term immunity Passive immunity

AP Biology What if the attacker gets past the B cells in the blood & actually infects some of your cells? You need trained assassins to kill off these infected cells! Attack of the Killer T cells!

AP Biology T cells  Cell-mediated response  immune response to infected cells  viruses, bacteria & parasites (pathogens) within cells  defense against “non-self” cells  cancer & transplant cells  Types of T cells  helper T cells  alerts immune system  killer (cytotoxic) T cells  attack infected body cells

AP Biology How do T cells know a cell is infected  Infected cells digest pathogens & MHC proteins bind & carry pieces to cell surface  antigen presenting cells (APC)  alerts Helper T cells MHC proteins displaying foreign antigens infected cell T cell antigen receptors T cell WANTED

AP Biology T cell response stimulate B cells & antibodies Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y YY Y Y killer T cell activate killer T cells or interleukin 1 interleukin 2 infected cell helper T cell activated macrophage

AP Biology HIV & AIDS  Human Immunodeficiency Virus  virus infects helper T cells  helper T cells don’t activate rest of immune system: T cells & B cells  also destroy T cells  Acquired ImmunoDeficiency Syndrome  infections by opportunistic diseases  death usually from secondary infections  pneumonia, cancer

AP Biology Immune system malfunctions  Auto-immune diseases  immune system attacks own molecules & cells  lupus  antibodies against many molecules released by normal breakdown of cells  rheumatoid arthritis  antibodies causing damage to cartilage & bone  diabetes  beta-islet cells of pancreas attacked & destroyed  multiple sclerosis  T cells attack myelin sheath of brain & spinal cord nerves  Allergies  over-reaction to environmental antigens  allergens = proteins on pollen, dust mites, in animal saliva  stimulates release of histamine

AP Biology

Immunity  The 3 lines of defense  Non-specific vs. specific  Acquired vs. passive immunity  Humoral vs. Cell-mediated response